If you have recently used Bitcoin to transfer money, you may realize that such a long waiting time for confirmation is not suitable for use as a currency. If you want your transaction to be packaged in the next block, you have to wait for this A transaction is confirmed on the blockchain 1-6 times. The waiting time ranges from 10 minutes to 60 minutes. Bitcoin’s transaction design was originally not like this. Before 2015, most Bitcoin transactions were instant. This feature is called 0 confirmation means 0 confirmation transaction At that time, it was much more convenient to use Bitcoin as a payment method than it is now. You only need to scan your mobile phone, and your transaction will be broadcast to the network and then it’s over. You don’t need to wait for multiple confirmations. There is also no need to worry about whether your own transaction will be packaged into the next block.
At that time, unconfirmed transactions can be trusted because the first broadcast transaction will be packaged into the next block. If someone tries to initiate a A double-spending transaction means sending the same money to a second address without confirmation. The second transaction will be ignored by the network. In this way, merchants can safely consider this transaction due to the loss of the ability to double-spend or cancel the transaction. The transaction will definitely be confirmed in the next block and you don't have to wait for instant transactions. It was very reliable until the Bitcoin Core team decided to introduce the so-called fee market strategy. Keep small blocks and the fees will increase to what users are willing to pay for security. The upper limit of the fee With the ever-increasing transaction fees and full blocks, if your transaction fee is low, your transaction may be stuck in the mempool for weeks. To solve this problem, Bitcoin core has added a new feature. ——Replace-By-Fee (RBF) This function allows you to double spend your own transaction. The original intention of RBF is that when your transaction is stuck in the memory pool due to insufficient handling fees, you can pay a higher fee.
Fee to rebroadcast this transaction (replacing the original one) This increases the possibility of the transaction being packaged in the next block. Unfortunately, this approach destroys 0 confirmation. With RBF when you use Bit After buying a product with coins, you can leave the store and rebroadcast a transaction with a higher fee to transfer the money back to your own address, so that you get back the remaining money after deducting the miner's fee. This forces the merchant to only You can trust transactions that have been confirmed by the blockchain. This is why we have to wait for a long time today. If Bitcoin develops into a stored value system instead of a currency, waiting for confirmation time will not be a problem. But for those who use Bitcoin on a daily basis Those who want to use Bitcoin as a currency will initiate a hard fork (BCH). The BCH branch removes RBF and expands the block size so that 0 confirmation can still be done. Normal use Currently, 0 confirmation is still the most reliable and tested way of instant transactions on the decentralized blockchain, but It is like most things in the cryptocurrency system.
In theory, as long as you use enough resources, you can still find possible attack methods. Technically, even if RBF is removed, it is still possible to double spend a transaction. If you buy Experts premeditated and auspicious stars are willing to spend a huge amount of resources, it is still possible to double-spend successfully. The problem is that most of this type of double-spend transactions are not worth the loss (it is difficult for attackers to profit from it) Even so, you are on the BCH chain Most of the 0-confirmation transactions are still very safe, but if you want to sell a Lamborghini or a luxury house to a cryptocurrency boss, you'd better wait for a few confirmations.
